Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accrued Liabilities And Other Liabilities [Abstract]
Accrued expenses	$ 183,261	$ 163,400
Accrued employee cost	182,211	179,360
Deferred transition revenue	47,317	50,552
Statutory liabilities	44,125	36,878
Retirement benefits	19,810	17,616
Derivative instruments	14,527	4,777
Advance from customers	27,678	21,969
Earn-out consideration	6,687	6,885
Other liabilities	13,607	15,461
Capital lease obligations	1,520	1,349
Accrued expenses and other current liabilities, net	$ 540,743	$ 498,247